Rebar clip for joining different size bars

ABSTRACT

A rebar clip is provided for joining a larger diameter rebar to a smaller diameter rebar transverse to the larger diameter rebar. In a first embodiment the clip includes diameter reducing tabs extending into upper arches of the clip for engagement with smaller diameter bars crossed on top of larger diameter bars. In a second embodiment the clip includes diameter reducing tabs extending into lower arches of the clip so that the clip may hold larger diameter bars on top of smaller diameter bars. A guide track for a clip applying gun is provided which allows for use with either version of clips and with clips of the same nominal diameter for joining equal size bars.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure is directed to resilient plastic clips for use injoining reinforcing bars, and particularly to a clip, and clip applyingapparatus for use therewith, which is suitable for joining bars ofdifferent sizes.

2. Description of the Prior Art

Resilient plastic clips have been proposed for use in joiningreinforcing bars for the construction of reinforced concrete structures.U.S. Pat. No. 5,626,436 to Dragone, and assigned to the Assignee of thepresent invention, discloses a resilient clip designed to connect asmaller diameter reinforcing bar transversely on top of a largerdiameter reinforcing bar.

U.S. Patent Application Publication No. 2006/0248844 to Kodi, disclosesa resilient clip for connecting reinforcing bars of equal diameter. Theclip of Kodi U.S. Patent Application Publication 2006/0248844 isdesigned to connect bars of equal diameter either in a parallelorientation or a transverse orientation.

U.S. Patent Application Publication No. 2008/0115449 to Kodi discloses abar connecting apparatus for use in applying clips like those of theKodi U.S. Patent Application Publication No. 2006/0248844 to bars ofequal diameter.

There is a continuing need for improvements in the design of such clipsand apparatus for applying the same.

SUMMARY OF THE INVENTION

In one embodiment a rebar clip is disclosed for joining a larger nominaldiameter rebar and a smaller nominal diameter rebar crossedperpendicularly to each other. The clip includes a clip body, a lowerpair of aligned partially circular lower lateral openings defined in theclip body and aligned in a first direction, and an upper pair of alignedpartially circular upper lateral openings defined in the clip bodytransversely to the first direction. Both the lower pair of lateralopenings and the upper pair of lateral openings are of the largernominal diameter. The clip body is downwardly open below both the lowerand upper pairs of lateral openings so that the clip can be presseddownward over the crossed larger and smaller nominal diameter rebars. Apair of opposed diameter reducing tabs extend toward each other into thelateral openings of one of said lower and upper pairs of lateralopenings to engage the smaller nominal diameter rebar.

When the diameter reducing tabs are located within the lower pair oflateral openings the clip can hold the larger nominal diameter rebar inplace above the smaller nominal diameter rebar.

When the diameter reducing tabs are located within the upper pair oflateral openings the clip can hold the smaller nominal diameter rebar inplace above the larger nominal diameter rebar.

In an embodiment, the diameter reducing tabs are located within theupper pair of lateral openings, and the tabs of each one of the upperlateral openings define a vertical slot therebetween for receiving aguide bar. A string of such clips, each of the clips being substantiallyidentical, are joined together with the vertical slots between tabsbeing aligned with each other for receiving the guide bar to guide thestring of clips.

In another embodiment a rebar clip is provided for joining a largerdiameter rebar to a smaller diameter rebar transverse to the largerdiameter rebar. The rebar clip includes a clip body defined along x, yand z orthogonal directions. The clip body includes first and secondpairs of resilient legs extending in the z-direction and defining firstand second lower arches aligned parallel to the x-direction. The clipbody includes first and second pairs of resilient arms extending in thez-direction away from the legs. The arms define first and second uppercradles aligned parallel to the x-direction. The clip body includesfirst and second bridges joining distal ends of the first pair of armsto distal ends of the second pair of arms. The bridges and the armsdefine first and second upper arches aligned parallel to they-direction. The lower arches, the upper cradles and the upper archeseach include curved portions of the larger diameter. Pairs of diameterreducing tabs extend into either the lower arches or the upper archesfor engaging the smaller diameter rebar.

In an embodiment the diameter reducing tabs extend into the lower archesso that the clip can hold the larger diameter rebar in place above thesmaller diameter rebar.

In another embodiment, the diameter reducing tabs extend into the upperarches so that the clip can hold the smaller diameter rebar in placeabove the larger diameter rebar.

In an embodiment a string of substantially identical size clips arejoined together with vertical slots between tabs in the upper archesaligned with each other for receiving a guide bar to guide the string ofclips.

In an embodiment an apparatus is provided for applying a clip to firstand second reinforcing bars. The apparatus includes a barrel having adistal end and a clip receiving cavity. A hammer is received in thebarrel. A main drive is connected to the hammer for reciprocating thehammer within the barrel. A trigger assembly is connected to the maindrive to actuate reciprocation of the hammer. A clip track is connectedto the barrel. The clip track is aligned with the cavity for guiding astring of frangibly connected clips into the cavity. The clip track hasa longitudinal axis extending transversely from the barrel. The cliptrack has a cross-sectional shape perpendicular to its longitudinalaxis, which cross-sectional shape has a base portion having a base widthdefined between two sides, and a neck portion having a neck widthdefined between two neck sides. The neck width is less than the basewidth. The neck portion can be received between tabs in a string ofclips for guiding the string of clips.

In another embodiment an apparatus for applying a clip to first andsecond reinforcing bars includes a barrel having a clip receiving cavitysized to receive a clip for joining two equal diameter crossed rebars ofa first diameter. The apparatus includes a clip track connected to thebarrel and aligned with the cavity for guiding a string of clips intothe cavity. The clip track has a base portion having a base thickness,and the clip track has a neck portion extending from the base portionand having a neck thickness less than the base thickness. This permitsthe clip track to be used to selectively receive and guide into thecavity either a string of clips for joining two equal diameter crossedrebars or a string of clips for joining a smaller diameter rebar to arebar of the first diameter.

Numerous objects, features and advantages of the present invention willbe readily apparent to those skilled in the art upon a reading of thefollowing disclosure when taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a resilient clip.

FIG. 2 is an elevation view of the clip of FIG. 1 showing an upper archhaving a pair of diameter reducing tabs.

FIG. 3 is an elevation sectioned view taken along line 3-3 of FIG. 2.

FIG. 4 is an enlarged view of the area encircled and designated by thenumeral 4 in FIG. 2.

FIG. 5 is a side view of a string of clips like those of FIGS. 1-4,wherein each of the clips is shown in a side view similar to FIG. 3.

FIG. 6 is a perspective view of a clip like that of FIGS. 1-4 in placeupon two transversely crossed rebars, with a smaller diameter rebar ontop of a larger diameter rebar.

FIG. 7 is a perspective view of a clip like that of FIGS. 1-4 showingthe joining of two parallel bars of the larger diameter.

FIG. 8 is a perspective view of another embodiment of a rebar clip.

FIG. 9 is a side elevation view of the clip of FIG. 8 showing a pair ofdiameter reducing tabs extending into a lower arch.

FIG. 10 is an elevation sectioned view of the clip of FIG. 9 taken alongline 10-10 of FIG. 9.

FIG. 11 is a bottom view of the clip of FIG. 9.

FIG. 12 is an enlarged view of the encircled area designated 12 in FIG.9.

FIG. 13 is a side elevation view of a string of clips like those of FIG.9.

FIG. 14 a perspective view of a clip like that of FIGS. 8-12 in placeover a pair of crossed reinforcing bars wherein a larger diameter bar isheld on top of a smaller diameter bar.

FIG. 15 is a perspective view of a clip like that of FIGS. 9-12 holdinga larger diameter bar in place above and parallel to a smaller diameterbar.

FIG. 16 is a perspective view of a clip applying apparatus or gun forapplying clip strings like those of FIGS. 5 and 13 to connectreinforcing bars together.

FIG. 17 is a left side elevation view of the clip applying apparatus ofFIG. 16.

FIG. 18 is a perspective view of the clip track of the clip applyingapparatus of FIGS. 16 and 17, showing a clip like that of FIGS. 1-4 inplace thereon.

FIG. 19 is an end view of the clip track and clip assembly of FIG. 18.

FIG. 20 is a perspective view similar to FIG. 18 of the proximal end ofthe clip track, showing a modified version thereof including oneembodiment of a resiliently biased clip retainer.

FIG. 21 is a side elevation view of the clip track of FIG. 20.

FIG. 22 is a perspective view of another embodiment of a clip tracksimilar to FIG. 18, having a second embodiment of a resiliently biasedclip retainer shown therein.

FIG. 23 is a side elevation view of the clip track of FIG. 22.

FIG. 24 is a side elevation view of the clip track of FIGS. 20 and 21showing the string retainer biased laterally outward away from the cliptrack and in engagement with a clip as it would be to hold a string ofsuch clips in place upon the clip track.

FIG. 25 is a perspective schematic view showing a brace for supporting adistal end of the clip track from a handle of the clip applying gun.

FIG. 26 is a perspective view of a prior art clip in place on twotransversely crossed rebars of equal diameter.

FIG. 27 is an elevation sectioned view similar to FIG. 10, showing analternative version of the lower diameter reducing tabs.

DETAILED DESCRIPTION

Referring now to FIGS. 1-7, a first embodiment of a rebar clip is shownand generally designated by the numeral 10. As seen in FIG. 6, the rebarclip 10 can join a larger nominal diameter rebar 12 to a smaller nominaldiameter rebar 14 crossed perpendicularly relative to each other.

The rebar clip 10 includes a clip body 16. The clip body 16 can bedescribed as being defined along x, y and z orthogonal directions. Thex, y and z directions are illustrated for example in FIGS. 2 and 3,wherein the z-direction represents the direction parallel to the heightof the clip, and the x and y directions define planes generally parallelto the planes in which the rebars such as 12 and 14 will extend.

The clip body includes first and second pairs of resilient legs 18 and20. Each pair of legs includes two legs such as 18A and 18B seen in FIG.3. The pairs of resilient legs 18 and 20 extend in the z-direction anddefine first and second lower arches 22 and 24 aligned parallel to thex-direction.

The clip body 16 further includes first and second pairs of resilientarms 26 and 28 extending in the z-direction away from the legs 18 and20. Each pair of arms such as pair 26 includes two arms 26A and 26B. Thearms define first and second upper cradles 30 and 32 which are alignedparallel to the x-direction.

The clip body 16 includes first and second bridges 34 and 36 joiningdistal ends of the first pair of arms 26A, 26B to the second pair ofarms 28A, 28B. The bridges 34 and 36 and the arms 26 and 28 define firstand second upper arches 38 and 40 aligned parallel to the y-direction.

As is thus seen in FIGS. 2 and 3, and the lower arches 22 and 24, theupper cradles 30 and 32, and the upper arches 38 and 40 each includecurved portions having a diameter substantially equal to the diameter ofthe larger diameter rebar 12.

Each of the upper arches 38 and 40 has a pair of diameter reducing tabs42 and 44, respectively. The pair of tabs 42 includes tabs 42A and 42B.The pair of tabs 44 includes tabs 44A and 44B.

In the embodiment shown in FIGS. 1-7, the diameter reducing tabs 42 and44 extend into the upper arches 38 and 40 so that the clip 10 can holdthe smaller diameter rebar 14 in place above the larger diameter rebar12.

As is best seen in the enlarged view of FIG. 4, each pair of thediameter reducing tabs such as 42A and 42B includes opposed obliquelydownward facing concave corners such as 46A and 46B for engaging thesmaller diameter rebar from above. Similar corners 48A and 48B arepresent on the tabs 44A and 44B.

As best seen in FIGS. 2 and 4, each of the pairs of tabs such as 42 and44 defines a vertical slot 50 therebetweeen for receiving a guide bar orguide track 124 such as shown for example in FIGS. 18 and 19.

FIG. 5 illustrates a string of clips each identical to the rebar clip 10just described, the clips being joined together with the vertical slots50 between tabs 42 and 44 aligned with each other for receiving theguide bar to guide the string of clips.

As is best seen in FIG. 3, the first and second lower arches 22 and 24can be described as a lower pair of aligned partially circular lowerlateral openings defined in the clip body 16 and aligned in a firstdirection, namely the x-direction.

As best seen in FIG. 2, the first and second upper arches 38 and 40 canbe described as an upper pair of aligned partially circular upperlateral openings defined in the clip body 16 transversely to the firstdirection, namely aligned in the direction y.

It is noted that the circular portions of the upper arches 38 and 40 areof the same nominal diameter as are the lower arches 22 and 24, whichare equal to the nominal diameter of the larger diameter rebar 12.

The clip 10 can be described as being downwardly open below the lowerarches 22, 24 and the upper arches 38, 40 so that the clip 10 can bepressed downward over the crossed larger and smaller diameter rebars 12and 14 as shown in FIG. 6.

It is noted that although the clip 10 is primarily intended for use injoining smaller diameter bars transversely on top of larger diameterbars as shown in FIG. 6, the clip 10 can also be utilized as shown inFIG. 7 to join two parallel bars of equal diameter.

The Embodiment of FIGS. 8-15

Referring now to FIGS. 8-15, an alternative embodiment of the clip isshown and generally designated by the numeral 60. As will be seen, theclip 60 is similar to the clip 10, except in the clip 60 the diameterreducing tabs are placed within the lower arches rather than the upperarches, so that the tabs can hold the smaller diameter rebar 14 in placebelow the larger diameter rebar 12 as shown in FIG. 14.

Thus the rebar clip 60 has a clip body 62 having first and second pairsof legs 64 and 66 defining first and second lower arches 68 and 70. Theclip body 62 includes first and second pairs of arms 72 and 74 definingfirst and second upper cradles 76 and 78.

First and second bridges 80 and 82 join the first pair of arms 72 to thesecond pair of arms 74. The arms and bridges together define the firstand second upper arches 84 and 86.

In the embodiment of FIGS. 8-15, there are first and second pairs ofdiameter reducing tabs 88A and 88B, and 90A and 90B, extending into thelower arches 68 and 70, respectively, so that the clip 60 can hold thelarger diameter rebar 12 in place above the lower diameter rebar 14,with the tabs 88 and 90 engaging the lower diameter rebar 14 from below.

As is best seen in FIG. 12, each pair of diameter reducing tabs includesopposed obliquely upward facing concave corners such as 92A and 92B. Itis the corners such as 92A and 92B of the tabs which engage the smallerdiameter rebar from below.

As best seen in FIG. 9, each pair of legs such as 64A-64B defines alower gap dimension 94.

As is best seen in FIG. 9, each leg of the pair of legs such as 64A and64B are downwardly flared away from each other as indicated at 96 and 98to provide a tapered guide into the gap 94 for a lower one of thecrossed rebars being joined. In the embodiment of FIGS. 8-15 that lowerrebar is the smaller diameter rebar 14.

As best seen in FIGS. 9 and 12, the tabs such as 88A and 88B associatedwith each pair of legs define a vertical path 100 having a widthsubstantially equal to the gap dimension 94.

As seen in FIG. 10, the legs such as 64A and 66A each have a legthickness 102 and 104, respectively, in the x-direction. Additionally,the tabs such as 88A and 90A each have a tab thickness in thex-direction, the tab thicknesses being equal to the leg thicknesses 102and 104, respectively. Furthermore, as best seen in FIGS. 8 and 10, thetabs are flush with the sides of the legs closest to the other pair oflegs.

FIG. 13 shows a string of clips identical to the clip 60, the clipsbeing joined together with their upper arches 84 and 86 aligned witheach other so that the string of clips can be received upon a guide barin a manner like that shown in FIGS. 17, 18 and 24.

Although the clip 60 is primarily designed for use in joining largerdiameter bars on top of transversely oriented smaller diameter bars asillustrated in FIG. 14, it is noted that the clip 60 can also beutilized to join a smaller diameter bar to a larger diameter bar inparallel orientation as shown in FIG. 15.

In an alternative version of the clip 60 shown in FIG. 27, the tabs suchas 88A and 90A have tab thicknesses 106 and 108 in the x-direction, thetab thicknesses being less than the leg thicknesses 102 and 104,respectively. Again, the tabs may be flush with the sides of the legsclosest to the other pair of legs.

Methods of Manufacturing the Clips

The clips such as 10 and 60 described above are preferably injectionmolded from resilient plastic material.

It will be understood that when designing a system utilizing clipapplying guns and clips like those just described, it is desirable forthe system to provide the ability to join all of the types of rebar thatwill be needed, including parallel connections, transverse connections,connections between equal size bars, and connections between differentsize bars.

It will further be understood that it is desirable to provide such asystem with the lowest possible manufacturing cost, and with thesimplest possible mechanisms for use in the field.

It will be appreciated when viewing the clips 10 and 60 described above,that if the diameter reducing tabs were eliminated, the clip body issubstantially identical to that such as disclosed in U.S. PatentApplication Publication No. 2006/0248844 which is designed for paralleland/or transverse attachment of bars of equal diameter.

It will also be understood that each clip applying gun such as thatillustrated in FIGS. 16 and 17 and described below, will be designed foruse with one nominal size clip which will fit properly within itsinternal clip chamber, and that clip size will be associated with anominal diameter rebar for which the clip is designed.

The present invention provides a system wherein a clip body which hasall of the external dimensions substantially equal to a clip body likethat of U.S. Patent Application Publication No. 2006/0248844 designedfor use with bars of equal diameter, can be modified to accept a bar ofa smaller diameter in either its upper or lower arches.

This will permit the same clip applying gun to be used with clipsdesigned for joining equal size bars of the larger nominal diameter, andalso for joining one bar of the larger nominal diameter with another barof the smaller nominal diameter.

Furthermore, the manufacture of the clips themselves is economized inthat injection molds which have already been set up for manufacturingclips for use with bars of equal diameter, such as the clip of U.S.Patent Application Publication No. 2006/0248844, can be easily modifiedby having inserts placed therein to define the shape of the diameterreducing tabs such as described above, and thus the same molds can beused for molding clips including the diameter reducing tabs, thus savinggreatly on mold construction costs.

The Clip Applying Gun

Referring now to FIGS. 16-25, the details of construction of a clipapplying gun apparatus 110 are shown. The clip gun 110 can generally bedescribed as having a barrel 112 having a distal end 114 with a clipreceiving cavity 116 defined within the barrel 112. In the view of FIG.17 the location of the clip receiving cavity 116 internally within thebarrel 112 is shown in dashed lines. A hammer 118 is reciprocallyreceived within the barrel 112. Again, in FIG. 17 the hammer and itslocation within the barrel is shown in dashed lines. A main drivemechanism 120 is connected to the hammer for reciprocating the hammer118 within the barrel. A trigger assembly 122 is connected to the maindrive 120 to actuate reciprocation of the hammer 118.

The various internal details of construction of the clip applying gun110 are shown for example in Applicant's pending U.S. patent applicationSer. No. 12/762,409, filed Apr. 19, 2010 entitled Clip Gun WithPneumatic Feed, and assigned to the Assignee of the present invention,the details of which are incorporated herein by reference.

The clip applying gun 110 includes a clip track 124 aligned with theclip receiving cavity 116 for guiding a string 126 of frangiblyconnected clips into the cavity 116. It will be understood that thestring of frangibly connected clips 126 may either be a string of clips10 as shown in FIG. 5 having diameter reducing tabs in their upperarches, or a string of clips 60 such as shown in FIG. 13 having diameterreducing tabs in their lower arches, or a string of clips such as thoseillustrated in U.S. Patent Application Publication No. 2006/0248844designed for use solely with equal diameter bars. As will be furtherexplained below, the clip track 124 has been designed so as to besuitable for guiding any of those three types of clip strings, and theexternal dimensions of the clips of each of those types of clip stringswill be substantially equal and will be associated with the nominaldiameter of the larger nominal diameter bar 12.

The clip track or guide bar 124 has a cross-sectional shape as best seenin FIG. 19 perpendicular to its longitudinal axis 127 which isidentified in FIG. 18. The longitudinal axis 127 is parallel to the yaxis of the clips 10 and 60 described above. In FIG. 18 adjacent to thesample of the clip 10 shown in place upon the clip track 124 is adirectional representation of the x, y and z axes of the clip 10.

The cross-sectional shape of the clip track 124 has a base portion 128having a base width 130 defined between two base sides 132 and 134, andhas a neck portion 136 having a neck width 138 defined between two necksides 140 and 142.

As best seen in FIG. 19, the neck width 138 is less than the base width130, and in the example shown, the neck width 138 is less than one halfthe base width 130.

In the example of FIGS. 18 and 19 the two base sides 132 and 134 aresubstantially parallel to each other, and the two neck sides 140 and 142are substantially parallel to each other.

As best seen in FIG. 18, the neck portion 136 may extend for the entirelongitudinal length of the clip track 124.

As best seen in FIG. 19, the neck portion 136 has a neck height 144which in the example shown is greater than one half of the base width130. It is noted that the neck height 144 can also be described as beinggreater than the radius of the circular portion of the upper arches 38and 40.

Thus the clip track 124 can accommodate a clip string 126 of a nominalsize corresponding to the larger nominal diameter rebar 12, regardlessof whether that clip string includes diameter reducing tabs in its upperarches. If the clips are like clip 10 as illustrated in FIG. 18, theneck portion 136 of clip track 144 will be closely received within thevertical slots 50 between the diameter reducing tabs 42 and 44. If theclips do not include diameter reducing tabs in their upper arches, thecentermost highest portion of the upper arch will simply ride upon alaterally outermost edge 146 of the neck portion 136 of clip track 124.

The clip track 124 permits the clip applying apparatus 110 toselectively receive and guide into the cavity either a prior art stringof clips for joining two equal diameter crossed rebars, such asillustrated for example in FIG. 26, or either of the strings of clipsdescribed with regard to FIGS. 1-15 above for joining a smaller diameterrebar to a larger diameter rebar. Particularly, when the clips of FIGS.1-7 having diameter reducing tabs in their upper arches are utilized,the neck portion 136 of clip track 144 is closely received within theslots 50 of the clips to guide the clip string along the clip track.

Thus the clip track 124 allows a clip applying apparatus which waspreviously designed for use with clips designed solely for joining barsof equal diameter, to now be used with clips for joining smaller bars toa bar of the larger diameter.

The Clip Retainers

Turning now to FIGS. 20-24, an optional feature of a retainer clipdesigned for use with the clip track 124 is shown.

In a first embodiment shown in FIGS. 20, 21 and 24, a clip stringretainer 148 is pivotally connected to the neck portion 136 by pivot pin150. A biasing spring 152 is schematically illustrated in FIG. 21 andbiases the clip retainer 148 from the closed or retracted position ofFIGS. 20 and 21 toward an open or extended position as shown in FIG. 24.In FIG. 24 the manner in which the retainer 148 would engage one of theclips 10 of the clip string is illustrated.

In an alternative embodiment as shown in FIGS. 22 and 23, a clip stringretainer 154 is pivotally connected at 156 and is biased toward itsextended position by a spring schematically shown as 158.

The Support Brace

One final optional feature for the clip applying gun 110 is shown inFIG. 25. In FIG. 25 a barrel handle portion 160 of the gun 110 isschematically shown, as is a distal end portion of the clip track 124. Abrace 122 is shown attached to the handle 160 via bolt or other suitablefastener 164 and attached to the distal end portion of the clip track112.

It is noted in reference to FIG. 18, that the distal end portion of cliptrack 124 has two fastener holes 166 and 168 defined therein throughwhich screws or other suitable fasteners extend to connect the cliptrack 124 to the brace 162.

Thus it is seen that the apparatus and methods of the present inventionreadily achieve the ends and advantages mentioned as well as thoseinherent therein. While certain preferred embodiments of the inventionhave been illustrated and described for purposes of the presentdisclosure, numerous changes in the arrangement and construction ofparts and steps may be made by those skilled in the art, which changesare encompassed within the scope and spirit of the present invention asdefined by the appended claims.

What is claimed is:
 1. An apparatus for applying a clip to first andsecond reinforcing bars, comprising: a barrel having a distal end and aclip receiving cavity; a hammer received in the barrel; a main drive,connected to the hammer, for reciprocating the hammer within the barrel:a trigger assembly, connected to the main drive, to actuatereciprocation of the hammer; and a clip track connected to the barrel,the clip track aligned with the cavity for guiding a string of frangiblyconnected clips into the cavity, the clip track having a longitudinalaxis extending transversely from the barrel, the clip track having across-sectional shape perpendicular to its longitudinal axis, thecross-sectional shape having a base portion having a base width definedbetween two base sides, and the base portion having a base height, and aneck portion extending from the base portion above the base height, theneck portion having a neck width defined between two neck sides, theneck width being less than one half the base width, and the neck portionhaving a neck height above the base of less than the base height.
 2. Theapparatus of claim 1, wherein: the base sides are substantially parallelto each other.
 3. The apparatus of claim 1, wherein: the neck sides aresubstantially parallel to each other.
 4. The apparatus of claim 1,wherein: the neck portion extends for the entire longitudinal length ofthe track.
 5. The apparatus of claim 1, wherein: the neck height isgreater than one half of the base width.
 6. The apparatus of claim 1,further comprising: a clip string retainer connected to the neck portionof the clip track, the retainer being movable relative to the clip trackbetween a retracted position and an extended position, the retainerextending beyond the neck portion when in the extended position; and aspring biasing the retainer toward the extended position.
 7. Theapparatus of claim 1, further comprising: a handle extending laterallyfrom the barrel; and a brace attached to the handle and to a distal endof the clip track, to support the distal end of the clip track.
 8. Theapparatus of claim 1, wherein: the clip receiving cavity is sized toreceive a clip having a nominal size corresponding to a standard clipfor joining two crossed rebars of the same given nominal diameter; andthe neck portion of the clip track permits the apparatus to receive onthe clip track a modified clip for joining a smaller diameter rebarcrossed on top of a larger rebar of the given nominal diameter.
 9. Anapparatus for applying a clip to first and second reinforcing bars,comprising: a barrel having a clip receiving cavity sized to receive aclip for joining two equal diameter crossed rebars of a first diameter;and a clip track connected to the barrel and aligned with the cavity forguiding a string of clips into the cavity, the clip track having a baseportion having a base thickness and a base height, and the clip trackhaving a neck portion extending from the base portion and having a neckthickness and a neck height, the neck thickness being less than one halfthe base thickness, and the neck height being less than the base height,so that the clip track can selectively receive and guide into the cavityeither a string of clips for joining two equal diameter crossed rebarsor a string of clips for joining a smaller diameter rebar to a rebar ofthe first diameter.
 10. The apparatus of claim 9, wherein: the neck hastwo substantially parallel neck sides, the neck thickness being definedbetween the neck sides.
 11. The apparatus of claim 10, wherein: the basehas two substantially parallel base sides, the base thickness beingdefined between the base sides.
 12. The apparatus of claim 9, wherein:the neck height is being greater than one-half the base thickness. 13.The apparatus of claim 9, further comprising: a string of frangiblyconnected clips received on the clip track, each of the clips havingupper and lower arches sized to receive two equal diameter crossedrebars of the first diameter.
 14. The apparatus of claim 9, furthercomprising: a string of frangibly connected clips received on the cliptrack, each of the clips having a lower arch sized to receive a bar ofthe first diameter, and each of the clips having an upper arch includinga pair of diameter reducing tabs defining a slot therebetween; whereinthe neck of the clip track is received in the slots of the clips.
 15. Anapparatus for applying a clip to first and second reinforcing bars,comprising: a barrel having a clip receiving cavity sized to receive aclip for joining two equal diameter crossed rebars of a first diameter;a clip track connected to the barrel and aligned with the cavity forguiding a string of clips into the cavity, the clip track having a baseportion having a base thickness, and the clip track having a neckportion extending from the base portion and having a neck thickness lessthan the base thickness, so that the clip track can selectively receiveand guide into the cavity either a string of clips for joining two equaldiameter crossed rebars or a string of clips for joining a smallerdiameter rebar to a rebar of the first diameter; and a string offrangibly connected clips received on the clip track, each of the clipshaving upper and lower arches sized to receive two equal diametercrossed rebars of the first diameter.
 16. An apparatus for applying aclip to first and second reinforcing bars, comprising: a barrel having aclip receiving cavity sized to receive a clip for joining two equaldiameter crossed rebars of a first diameter; a clip track connected tothe barrel and aligned with the cavity for guiding a string of clipsinto the cavity, the clip track having a base portion having a basethickness, and the clip track having a neck portion extending from thebase portion and having a neck thickness less than the base thickness,so that the clip track can selectively receive and guide into the cavityeither a string of clips for joining two equal diameter crossed rebarsor a string of clips for joining a smaller diameter rebar to a rebar ofthe first diameter; and a string of frangibly connected clips receivedon the clip track, each of the clips having a lower arch sized toreceive a bar of the first diameter, and each of the clips having anupper arch including a pair of diameter reducing tabs defining a slottherebetween; wherein the neck of the clip track is received in theslots of the clips.